Land is the carrier of the production and living activities of human society and the basis of survival and development of all living organisms. With the continuous development of the social economy, the unreasonable use of land is becoming more and more serious, aggravating the deterioration of the ecological environment. Most studies in this field have mainly focused on land use changes and the corresponding impacts on the ecological environment, but relatively few studies have delinked the relationship between land use intensity and the ecological environment. Based on data on these two factors for Gansu Province from 1998 to 2017, we used the Tapio decoupling model to evaluate the decoupling relationship between land use intensity and ecological environment. From 1998 to 2017, the comprehensive land use intensity in Gansu province increased by 107.77%, and the comprehensive ecological environment index increased by 63.76%. In general, the relationship between land use intensity and ecological environment experienced five states, namely weak decoupling, strong negative decoupling, strong decoupling, expansive negative decoupling, and declining decoupling. During 1999–2013 and 2013–2016, land use intensity and ecological environment had decoupled, and the main reasons were as follows: (1) The Chinese government introduced a series of farmland protection policies and measures, controlled the area of newly added construction land, and reduced urban land expansion; (2) ecological restoration projects for mountains, forests, fields, lakes, and grassland strengthened the environmental protection in Gansu Province; and (3) in the process of economic development, the increased investment of technology and capital improved the land use efficiency, finally realizing the “double growth” of land use intensity and environmental quality. Based on these results, land use intensity and environmental quality are not necessarily contradictory, and a moderate improvement of land use efficiency and environmental protection can probably result in increased land use intensity and higher environmental quality.

The karst landforms in northeastern Sichuan Basin are widely developed, but the understanding of the geological characteristics, controlling factors, and spatiotemporal evolution process of karst caves is still unclear. The research object of this study is the Panlongdong karst cave in the northeastern Sichuan Basin. An outcrop geological survey was carried out, ¹⁴C isotope dating of stalactite was performed, carbon and oxygen isotope analysis was completed, and the formation process was identified. The interior of this cave is covered with karst sediments, and its original rocks are the Permian Wujiaping and Changxing formations, with secondary dissolution that has developed. The rock types, geological structure (fault, joint), and climate are the main factors behind the formation of the Panlongdong karst cave. The sedimentation of biogenic reefs and carbonate rocks is a fundamental geological condition for the development of karst processes. The geological structures provide channels for the dissolution of atmospheric precipitation. From 43.5 ka.B.P., six continuous changes in climate have intensified the formation of karst landforms. Warm, humid, and cold dry climate conditions have repeatedly occurred, and carbonate rocks have experienced varying degrees of karstification under the influence of climate. Through the four stages of structural breakup and surface dissolution, secondary cranny dissolution, selective dissolution, and detachment of rock mass and karst sediment formation, the Panlongdong karst cave was ultimately formed. The formation process of the Panlongdong karst cave is of great significance for understanding the evolution of the paleoenvironment in the northeastern Sichuan Basin.